But, despite the side-effects, Ms Roberts said she has been told the success rate from having the treatment has been put at between 67% and 82%.

She said: "I have never doubted that he was not going to be alive at the end of this, with or without treatment.

"I just felt that he would be much better off without the treatment and providing the body with what it needs to heal, not bombarding it with radiation, which is what we are taught to avoid.

"I don't understand why we are using it in hospitals. I find it barbaric and plain torture. Needlessly, children are suffering."

Legal fight: Mum Sally Roberts (Photo: PA)

She added that the course of treatment was "unnecessary" and went on: "They just come in with their conventional cure and it's worse than the condition itself."

Ms Roberts hit the headlines when she disappeared with Neon but both were found safe and well after a judge ordered a search.

She later apologised for vanishing and said that she had panicked.

Ms Roberts told the show: "Why did I take him away? Because I was being panicked into making a decision without being informed and I needed to gather more information.

"I asked them where they were getting their statistics from and they could only provide me with a study from the 1940s."

In December, a High Court judge ruled that Neon could receive radiotherapy for the tumour, against the wishes of Ms Roberts whose judgment, he said, "had gone awry".

Mr Justice Bodey dismissed Ms Roberts' attempt to prevent her son having radiotherapy treatment, and expressed concern over her decision-making regarding his welfare.

Ms Roberts, who had earlier failed in a similar legal bid to prevent surgeons performing a follow-up operation on Neon, feared that radiotherapy would cause long-term harm.

Mr Justice Bodey, who had been told by doctors that Neon could die within months without radiotherapy treatment, said he sympathised with the "nightmare" confronting Ms Roberts.

But he said he was worried that she had not grasped the seriousness of Neon's situation, and that the operation she opposed was life-saving.

The judge ruled that radiotherapy sessions could start and that Neon should live with his father Ben - who is separated from Ms Roberts - for the duration of his treatment.

And during the hearing in the Family Division of the High Court in London, he said that, in future, doctors would need only Mr Roberts' consent when making decisions about Neon's cancer treatment.

He said it was important that doctors were not hampered by a "stalemate" if parents took differing views.

Ms Roberts said her focus now was to try to offer as many natural therapies as possible to "eradicate side-effects of radiation" from Neon.

Professor Richard Grundy, a professor of paediatric neuro-oncology, told the show: "I think we all accept that we are using treatments that are fighting fire with fire but we do so with reasonable success."

He added: "We all accept that we are still using treatments that have significant side-effects but the notion that we are not doing anything to understand that is untrue."